And a 2014 study of migraine sufferers who were set off by odours found that 75 per cent named ‘perfume’ as the big trigger.

Kate has also explored the link between fragrance and asthma. She says: “Asthma sufferers are particularly susceptible to fragrance. One research paper noted: ‘Many patients complain that some odours worsen their asthma. Perfume and cologne are two of the most frequently mentioned offenders.’

These researchers found that, out of 60 asthmatic patients, 57 reported respiratory symptoms when they were exposed to common odours, including fragrance.

Meanwhile, another study found a link between asthma and air fresheners in 30 per cent of the respondents.